Preparation of perhaloacetyl peroxides



Dec. 10, 1957 c. w. WEBER ETAL 2,816,147

PREPARATION oF PERHALOACETYL PERoxIDEs Filed March 1955 J o 3 In xg m N N ff) n) Q o f S "1 D i v n N N 1 Q f2 0 N N m o Il'.

e" 9 Y v f` o m 9 s [LQ o mh] O o u( ulb! or so 2 rgvl 9 g3 Ik )'m dup 1-d gu 2 I Oo o m l,jen "im um 2( Z m0 (D- l o nA 4ag ma gf Y INVENTolLs L rl wlLLlAM S.BARNHART CHARLES W. WEBER V'BY 9M Y ATTORN YS United States Patent PREPARATION `0F' PE/RHAL'GACETYL "iP-EROXIDES Charles W. Weber,Jersey ,Cityyand Williams. Barnhart, Cranford, N. J., assignors, `by 'rnesne assign'nne'lits,y to Minnesota Mining Land `-Mami'actilrixlg Compal'r 'St.

Paul, Minn., a corporation of Delaware This invention relates to va Eprocess .for the continuous preparation of perhaloacetyl peroxidesand, morepart'icularly, to a continuous process Vfor'the preparation ofbistrichloroacetyl peroxide.

Perhaloacetyl peroxides, suchfas'bis-trichloroacetyl peroxide, are useful as polymerization promoters and are particularly etlicacious in the polyrneriza'i'onffofperhlogenated .ethylenes, such as chlorotrilluoro'ethylene and tetrailunroethylene. sSince Ithese peroxdes y.contain @no hydrogen, fragments :of the .promoter that may *be .fincorporated in the l:polymeric productdo not diminish the stability .of the polymer `or its .ability to @resist chemical attack by halogens or halogenated compounds. When perhalogenated olenicmonomers are polymerized inthe presence o f these `peroxides as promoters, polymers .are produced which have exceptional stability.

`Perhaloacetyl peroxides, such as bistricliloroacetyl peroxide, have previously `been `prepared in-a`batch"process in Vwhich sodium peroxide is suspended 'in a`2`l) fpercent brine solution and iscontacted with trichloroace'tyl liloride for a vperiod of one to three minutes at a-temperature'of about -15" C. The-organic peroxidelisfextractcd with trichlorouorornet'hane, separated, Yandstored celdas a solution. The general reactiunis'as l=follows:

CClaC HC1 f-lheat (or NaOH) NaCl) //O CClaC A2,816,147 Patented Dec. 10, 1957 ICC VJ2 The average yield of organic peroxide rpr'oduced by rthe batch process is about 60 to 65 percent of the theoretical yield and .the trichlorouoromethane solution contains somey trichloroacetyl chloride. .'I-he lbrine layerf-isfus1ially acidic, 1and contains peroxide, inorganic or organic, rboth properties being highly variable.

A clear solution -ofsodiumperoxide A'in brinefcamb'e preparedat0 1C. -withsevolutionof heat but :with ya loss of .to 505percent of'fthejqpenoxide activity. Once-made, thissolution i-s stablefior--ayperiod'of` hours. `Hovve'vergan analogous .solution can :be V:readily prepared `by adding e:30 percent liquid hydrogen peroxide toaqueo'us brine,made basic by the addition of l a 'base such as sodium-hydroxide, without .the `evolution fof heat ror y-`the loss :of peroxide. Flhis.solutionfisalso stable'ffor-'a periodlof hours. Hence, in the 5Npresent invention -a .fmixture of Yhydrogen .peroxide in -basic brine solution is used instead ofisodiumzperoxide in .andlordinarfy 'brinesolution.

The :processof Vthe present `:invention is ,performed in a reactor using `acounter-currentflowfof astreamfofl'a perha-logenated acetylhalide ad'mxed with va`halo'genatcd.l'iydrocarbon, suchv asA trvichlorouorontethane, to .arstreamfof hydrogenperoxide inb'asiobrine. Thislreactio'n may\co'n venient-ly -be performed in a ytower `in which a mixture of hydrogen peroxide in basic brine `is :introduced near the .bottom of the tower, anda mixture of trichloroacetyl .chloride vin trichloroubromethane is lintroduced at the top fof the tower. A ip'roduct mixture of bis=trichloroacetyl peroxide land trichlorouorometh'ane is removed mear the lbottom of th'e :tower as a productf'of :the process, while aqueous brine is removed `as an overhead fraction and passed :to a 4waste disposal. The tempera ture 4,in :the Treactio'rrszonefis maint-ained'between 0 C.-a"nd the .freezing temperature of `'the reaction mixture, `which is about 20 C. Generally, the `'rez'i'ction tempera'tilre should -be controlled within the `range -of about =-5 A,to 20 C.

The perhalogenated acetyl halide `which l'm'ay be used in theypro'cess of thepresent inventionrn'a'y beacom'pound such as trichloroacety-l chloride, triuoroacetyluofide, and the like, `and 'this vcompound .is 'dissolved in 'a 'fh'alogenalteid hydrocarbon, :such as 'trichlorouoromethane, to give V:V0.4 to 1.0 molar solution. The basic brine solution, 4with which the p'erhalogenated `acetyl halide is ireacted, vis 'preferably Asaturated at 'the reaction temperature and may contain as .much fas .'20 percent 'by 'weight Aof sodium .chlori'de. IIn addition, the solution should be made 4aboutf0.f-1 "to 3z0fmo'l-ariin a base, such as sodium hydroxide, and about 0.3 'fto l1.0 molar in hydrogen peroxide. Good-results 'have 4been obtained using an aqueous brine solutiomcontaining `20 :percent by Weight of `sodit'un t to tI2 minutes.

Referring to the accompanying drawings in which a flow diagram for the process of .the present invention is shown:

Figure l is a flow diagram showing the basic elements of the process but eliminating certain valves and the like, the use of which will be obvious to those skilled in the art, and

Figure 2 discloses one embodiment of the method employed to cool the heat transfer medium used in the process.

Referring to Figure l of the drawing, tanks 2 and 4 having the jackets 6 and 8, respectively, thereon are feed tanks containing a mixture of a halogenated hydrocarbon, such as trichlorofluoromethanc, and a perhalogenated acetyl halide, such as trichloroacetyl chloride. This mixture is maintained at a temperature below C. and transferred by means of a conduit 10, the pump 12, and the conduit 14 to the heat exchanger 16, where the mixture is further cooled to the reaction temperature which may be about to 20 C. The mixture is then transferred through the conduit 18 to the reactor-extractor tower 20 and is introduced into this tower at a point adjacent the top thereof. The tower 20 is also provided with a jacket 22, whereby a heat transfer medium may be passed through the jacket to maintain the reaction temperature in the desired range. The reactor-extractor is also provided with a motor 24 mounted on the top thereof having a shaft 26 connected thereto, the shaft having a plurality of propellers or other agitators 28 mounted thereon to insure intimate mixing of the reactants in the tower. The tower 20 is also provided with a plurality of thermocouple wells 30 having the thermocouples 32 mounted therein. The thermocouples 32 are connected by means of wires, not shown, to suitable recording instruments, not shown, for measuring the temperature within the tower 20.

The tanks 34 and 36, having the jackets 38 and 40, respectively, thereon contain 'a feed mixture of basic brine and hydrogen peroxide, this feed mixture being passed through the conduit 42, the pump 44, and the conduit 46 to heat exchanger 48, where the temperature of the mixture is further lowered to the reaction temperature in the tower 20. The mixture is then passed through the conduit 50 to the tower 20 and is introduced at a point adjacent the bottom of the tower. A vent tube 52 is connected to the conduit 50 to prevent a vapor lock in this conduit due :to the slow decomposition of hydrogen peroxide into water and oxygen.

As the feed mixture of hydrogen peroxide in basic brine is introduced into the bottom of the tower and the feed mixture of trichloroacetyl peroxide and trichlorouorometh-ane is introduced into the top of the tower 20, a reaction occurs resulting in the formation of bis-trichloroacetyl peroxide, good agitation being essential to produce high yields of product. The bis-trichloroacetyl peroxide product is removed from the tower 20 through the conduit 54 as a mixture with trichlorouoromethane, this mixture being passed `to the product receiver 56 having the jacket S8 thereon, where it is maintained as a solution until it is used. This peroxideis reported to show the explosive force of nitroglycerin, plus extreme sensitivity to heat and shock; therefore, utmost care must be taken at all times in handling this material. Aqueous brine is removed overhead from the tower 20 through the conduit 60, where it is passed to a sewer or other waste disposal.

Referring to Figure 2 of the drawings, a system is shown for cooling the heat exchange medium, which may be any liquid having a sutiiciently low freezing point such as methyl alcohol, acetone, a 60-40 mixture of ethylene glycol and water, trichloroethylene, or carbon tetrachloride. This system cools the heat transfer medium which is circulated in :the jackets on the feed tanks, the

'heat exchangers, the jacket on the reactor-extractor and the jacket on the product receiver.

The return conduit 62 returning the heat exchange medium for cooling is divided, and one portion of the heat exchange medium passes through the coil 64 which is immersed in a cooling bath in the tank 66, the cooling bath being maintained at a temperature of 70 C. with solid carbon dioxide. The heat exchange medium in the tank 68 is maintained at a temperature sutciently low to provide the desired reaction temperature in the tower 20 and may be at a temperature in the range of -5 to 20 C. The cooled heat exchange medium is then transferred by means of the conduit 70, the pump 72, and the conduit 74 to the jackets on the heat exchangers, the -tower 20, and the various tanks.

Instead of the trichlorofiuoromethane which is mixed with the trichloroacetyl chloride, other halogenated hydrocarbons may be used, such as trichlorotrifiuoroethane, carbon tetrachloride, chloroform, and dichlorotluoromethane.

The invention will be further illustrated by reference to the following specific example:

EXAMPLE l Bis-trichloroacetyl peroxide was prepared using a reactor 4.5 feet in height fabricated from 12 mm. inside diameter glass tubing and using a 7 mm. outside diameter glass rod for stirring. The stirring rod, without bearings, hung from a motor and rotated from 400 to 600 revolutions per minute. The volumes of the top separation zone, reaction zone, and bottom separation zone were 35 ml., 8S m1., and 20 ml., respectively.

The operating procedure lwas as follows: The coolant was circulated and adjusted to a temperature of 15 C., and blank solvents, i. e., trichlorouoromethane and basic brine, were pumped to the reactor-extractor, the feed rates being adjusted as desired. The agitator was started and adjusted so that the mixing zone was above the brine inlet. The feed was then switched to active solvents and run for a period of one-half to one hour to replace the blank solvents in the system.

The run was then started and both basic brine and trichlorouoromethane eluents were collected. Grab samples were obtained and analyzed as desired. The run was stopped by switching to blank solvents for a period of one-half to one hour; the reactor eluents were weighed and analyzed.

The results of the various runs are summarized in the table below. Inadequate mixing of reactants or inadequate contact time appeared to be the principal hindrances to maximum peroxide yields.

Strrer design was also considered, and a stirrer consisting of two 3 mm. outside diameter glass rods, placed in parallel to form a ligure 8 surface, showed better mixing than a single rod. Runs 3 and 4 (reaction volume: 107 ml.) suggested too much contact was resulting in excessive hydrolysis of the trichloroacetyl chloride. By lowering the alkali concentration in runs 5 and 6, yields were improved and hydrolysis of unreacted trichloroacetyl chloride was minimized.

The effect of increased contact time in a larger reactor having a diameter of 20 mm. and reaction volume of 187 ml. is shown in runs 7 and 8 to result in a maximum yield of 68.8 percent by weight of peroxide product. However, a change in the stirrer was necessary with the larger .diameter reactor, the stirrer used being a 7 ml. outside diameter glass tube having polyethylene vanes mounted thereon at 4inch intervals throughout the reaction zone.

Table- Continuous synthesis of bs-tchlaroacetyl peroxide R 0015F Brine C t t St' un 011 aC llTlllg Experiment No. time, time, rate, min. 001100013, Rate, 1111./ H2O2, Rate, mL] Excess, min. volts Mole mn. mole NaOH,M min. 1Q:

percent 40 8.0 60 1.05 3 8 0.441 0.8 7 8 6s 8.9 95 120 0. 9s a i1i 0. 36 0. s n slao 66 i s. 1 95 u v n 195 0.90 3 54 0.491 0.8 9.67 104 6.6 A90 60 0. 854 932563 0.456 0.8 1mg 237 7.1 s0 i l l 69 0.917 6% 0.422 0.4 ggg 32 6.5 s0

a 6 135 0.969 b 0.414 0.6 m15 9.05 7.7 s2

' 0.488 0s 55 11.1 7s s 6. 76 b 11. 1 7 150 0.927 5.04 8 125 0 874 gli l 0 459 0 s 9'0 33 11 6 72 u 2: 5 i b 9.7 l

Peroxide Solution Spent Brine Experiment No. Temp. range, C.

(RCOhOg, Yield, 00130001, M Recovered, H2O2, M pH Stirrer Type M Percent Percent 1- V-10 to -15 O` 195 37. 1 0. 534 50. 7 presentmi 11 rod. 2- -go ggg 0.464 47.3 ...ca 11 D2. b1

0 V Oper. T011 0S. 3 final grab v 53.1 i 0'227 25'2 '-do u {g.8. 4 -17 to v-20coo1a1:1t 0.183 42.8 0.118 13.4 -do- 11 D0. 5 -20 coolant 0.255 55.6 0.415 45.2 0.193 4.0 Do.

0. 1 1 o. 6 -20 to -25 coolant.. 0 280 52. 8 o* 248 23. 4 0.190

029 626 009 97 7m il`gn 10 all 1 -14 0.319 6&8 0,106 11.4 }preSent-' 6 polyethylene Valles.

ses se I From feed tank readings.

b From measured volume of reactor eiuent. 001311` carried out with spent brine.

It will be obvious to those skilled in the art that many modifications may be made within the scope of the present invention without departing from the spirit thereof, and the invention includes all such modifications.

We claim:

l. A process for the continuous preparation of a perhaloacetyl peroxide which comprises continuously countercurrently contacting in a contacting zone a mixture of an inorganic peroxide and a brine solution with a mixture of a perhalogenated acetyl halide and a halogenated hydrocarbon while maintaining the temperature in the zone between 0 C. and the freezing temperature of the mixture, and continuously recovering a mixture of the perhaloacetyle peroxide and the halogenated hydrocarbon as a product of the process.

2. A process for the continuous preparation of a perhaloacetyl peroxide which comprises continuously countercurrently contacting in a contacting zone a mixture of an inorganic peroxide and a basic brine solution with a mixture of a perhalogenated acetyl halide and a halogenated hydrocarbon while maintaining the temperature in the zone between 0 C. and the freezing temperature of the mixture, and continuously recovering a mixture of the perhaloacetyl peroxide and the halogenated hydrocarbon as a product of the process.

3. A process for the continuous preparation of a perhaloacetyl peroxide which comprises continuously countercurrently contacting in a contacting zone a mixture of an inorganic peroxide and a basic brine solution with a mixture of a perhalogenated acetyl halide and a halogenated methane while maintaining the temperature in the zone between 0 C. and the freezing temperature of the mixture, and continuously recovering a mixture of the perhaloacetyl peroxide and the halogenated methane as a product of the process.

4. A process for the continuous preparation of a perhaloacetyl peroxide which comprises continuously countercurrently contacting in a contacting zone a mixture of hydrogen peroxide and a basic brine solution with a mixture of a perhalogenated acetyl halide and trichlorofiuoromethane while maintaining the temperature in the zone between 0 C. and the freezing temperature of the mixture, and continuously recovering a mixture of the perhaloacetyl peroxide and trichloro'uoromethane as a product of the process.

5. A process for the continuous preparation of bistrichloroacetyl peroxide which comprises continuously countercurrently contacting in a contacting zone a mixture of hydrogen peroxide and a basic brine solution with a -mixture of trichloroacetyl chloride and trichlorofluoromethane While maintaining the temperature in the zone between 0 C. and the freezing temperature of the mixture, and continuously recovering a mixture of bis-trichloroacetyl peroxide and trichlorouoromethane as a product of the process.

6. A process for the continuous preparation of a perhaloacetyl peroxide which comprises continuously countercurrently contacting in a contacting zone a mixture of an inorganic peroxide and a brine solution with a mixture of a perhalogenated acetyl halide and a halogenated hydrocarbon while maintaining the temperature in the zone between 0 C. and the freezing temperature of the mixture, and continuously recovering a mixture of the perhaloacetyl peroxide and the halogenated hydrocarbon as a product of the process.

7. A process for the continuous preparation of a perhaloacetyl peroxide which comprises continuously countercurrently contacting in a contacting zone a mixture of an inorganic peroxide and a basic brine solution with a mixture of a perhalogenated acetyl halide and a halogenated hydrocarbon while maintaining the temperature in the zone between 0 C` and the freezing temperature of the mixture, and continuously recovering a' mixture of the perhaloacetyl peroxide and the halogenated hydrocarbon as a product of the process.

8. A process for the continuous preparation of a perhaloacetyl peroxide which comprises continuously countercurrently contacting in a contacting zone a mixture of an inorganic peroxide and a basic brine solution with a mixture of a perhalogenated acetyl halide and a halogenated methane while maintaining the temperature in the zone between 0 C. and the freezing temperature of the mixture, and continuously recovering a mixture of the perhaloacetyl peroxide and the halogenated methane as a product of the process.

9. A process for the continuous preparation of a perhaloacetyl peroxide which comprises continuously countercurrently contacting in a contacting zone a mixture of hydrogen peroxide and a basic brine solution with a mixture of a perhalogenatedy acetyl halide and trichloroiluoromethane while maintaining the temperature in the zone between 0 C. and the freezing temperature of the mixture, and continuously recovering a mixture of the perhaloacetyl peroxide and trichlorouoromethane as a product of the process.

10. A process for the continuous preparation of bistrichloroacetyl peroxide which comprises continuously countercurrently contacting in a contacting zone a mixture of hydrogen peroxide and a basic brine solution with a mixture of trichloroacetyl chloride and trichlorouoromethane while maintaining thegtemperature in the zone between'O" C. and the freezing temperature of the mixture, and continuously recovering from the bottom of the contacting zone a mixture of bis-trichloroacetyl peroxide and trichlorofluoromethane as a product of the process.

11. A process for the continuous preparation of bistrichloroacetyl peroxide which comprises introducing into the lower end of a vertically elongated reaction zone a mixture of hydrogen peroxide and a basic brine solution in continuous countercurrent ow to a mixture of trichloroacetyl chloride and trichlorofluoromethane while maintaining the temperature in the zone between 0 C. and the freezing temperature of the mixture, and recovering from the lower end of the reaction zone a mixture of bis-trichloroacetyl peroxide and trichlorouoromethane as a product of the process.

References Cited in the le of this patent UNITED STATES PATENTS 1,913,775 Straub .Tune 13, 1933 2,580,373 Zimmerman Dec. 25, 1951 2,700,662 Young et al. Jan. 25, 1955 2,771,492 Chapman et al Nov. 20, 1956 FOREIGN PATENTS 334,531 Great Britain Aug. 27, 1930 

1. A PROCESS FOR THE CONTINUOUS PREPARATION OF A PREHALOACETYL PEROXIDE WHICH COMPRISES CONTINOUSLY COUNTERCURRENTLY CONTACTING IN A CONTACTING ZONE A MIXTURE OF AN INORGANIX PEROXIDE AND A BRINE SOLUTION WITH A MIXTURE OF A PERHALOGENATED ACETYL HALIDE AND A HALOGENATED HYDROCARBON WHILE MAINTAINING THE TEMPERATURE IN THE ZONE BETWEEN 0*C. AND THE FREEZING TEMPERATURE OF THE MIXTURE, AND CONTINOUSLY RECOVERING A MIXTURE OF THE PERHALOACETYLE PEROXIDE AND THE HALOGENATED HYDROCARBON AS A PRODUCT OF THE PROCESS. 